HP CP6015dn Service Manual - Page 215

Fusing and delivery unit The fusing and delivery unit fuses the toner onto the paper and delivers the printed page into the output bin. It has the following controls to ensure optimum print quality: ● Loop control ● Pressure roller pressurization/depressurization control A sensor detects when the output bin is full, and the DC controller notifies the formatter. Loop control The loop control maintains even tension on the paper while it is moving through the fuser to prevent print-quality defects and paper-handling defects. ● If the fuser rollers rotate more slowly than the secondary transfer rollers, the paper warp increases and an image defect or paper crease occurs. ● If the fuser rollers rotate faster than the secondary transfer rollers, the paper warp decreases and the toner image is not transferred to the paper correctly, causing color misregistration. To prevent these problems, the loop sensor, located between the secondary transfer rollers and the fuser rollers, detects whether the paper is sagging or is too taut. The DC controller adjusts the speed of the fuser motor accordingly. Figure 5-43 Loop-control mechanism Fuser rolle r Pressure roller Loop sensor lever ITB SR13: Loop sensor Secondary transfer roller Media When the fuser roller and the pressure roller rotate slower than the secondary transfer roller, When the fuser roller and the pressure roller rotate faster than the secondary transfer roller, Loop sensor: off Loop sensor: on ENWW Pickup, feed, and delivery system 173